headers vs manifolds on a 318 2bbl difference ????

Lots of people like Thermoquads, but I picked up almost half a second in the quarter, and ET's were a LOT more consistent, when I swapped my 73 Duster 340's Thermoquad for a spread bore Holley 650. Also got better gas mileage, and the Holley didn't vapor lock. Also, the Holley's secondaries would start opening before full throttle, so you could pass someone on a two lane road without downshifting into second. The Thermoquad, either you couldn't make it because the primary barrels were so small, or you'd give it full throttle, kickdown into second, and WAAAAAAAAAA and you'd race around.

I have had great but limited results with TQs, really like them, but there were the cracking issues, and limited performance parts when I was actively messing/experimenting.
I would cede to anyone with experience with them .
I really enjoyed the Quadrajets I had to use in the past .